1. Field of the Invention
The invention relates to an improved gas discharge lamp with an interior optical-lighting film, in which a visible-light coating thereof is characterized in a specific distributed density.
2. Description of the Prior Art
In current art of the light-emitting elements, the typical structure therefore includes a transparent glass tube having an interior wall coated by a fluorescent or phosphorescent layer with a predetermined width, in which the fluorescent or phosphorescent layer is consisted of piling particles. Inside the transparent tube, an electroluminescence photo gas such as the Mercury gas, the Argon gas, the Xenon gas, the Neon gas and son on is filled. As the tube is electrically energized, the internal photo gas would be charged by the high electric potential to emit the corresponding ultraviolet light to illuminate the fluorescent or phosphorescent layer so as to have the tube to emit the visible light. The visible light then penetrates the fluorescent or phosphorescent layer as well as the transparent casing so as to perform as a lamp set.
For the aforesaid fluorescent or phosphorescent layer is formed by piling a plurality of tiny particles, in order to have the fluorescent or phosphorescent layer to absorb enough ultraviolet energy at a single projection, it is inevitable to increase the thickness of the fluorescent or phosphorescent layer, i.e. to increase the piling of the tiny particles. However, a disadvantage from increasing the thickness of the fluorescent or phosphorescent layer is to decrease the penetration rate of the visible lights. It is noted that, for the visible lights, the fluorescent or phosphorescent layer reduce the transparency of the tube. Hence, for the skill person in the art, a preferred thickness of the fluorescent or phosphorescent layer based on an acceptable penetration rate of the visible light is determined by firstly choosing a fixed ultraviolet light source, then adjusting the thickness of the fluorescent or phosphorescent layer, and finally determining the thickness of the fluorescent or phosphorescent layer by evaluating the corresponding illuminus of the tube. In practice, a thinner layer of piled particles implies that some of the ultraviolet energy is lost or wasted because of fewer particles in the piling being unable to absorb completely the projected ultraviolet energy. However, even in such a circumstance, the accumulated piling number of the particles in the fluorescent or phosphorescent layer is summed up to 4 or 5 layers at least and 7 or 8 layers at most (referred to FIG. 18). Definitely, such a particle piling does also form a substantial obstacle to the visible lights.
Referring now to FIG. 37, a top view of a typical visible light layer under a scanning electron microscopy (SEM) is shown, in which a solid arrangement of particles in the visible light layer is clearly observed.
In practice, the fluorescent or phosphorescent layer coated inside the light-emitting element would face directly the internal electric-energized ultraviolet light and thus would be the most illuminated area there around. However, for the visible light produced by energizing the fluorescent or phosphorescent layer, the thickness of the fluorescent or phosphorescent layer is inevitably performed as an obstacle wall against the penetration of the visible light. Therefore, upon the aforesaid arrangement, the illumination efficiency of the light tube is definitely low. It is straightly forward that a thinner fluorescent or phosphorescent layer is expected to increase the light penetration rate of the visible lights, but yet such a change would lead to a low absorption rate of the source ultraviolet lights. In the art, it is hard to locate an optimal pair of the penetration rate of the fluorescent or phosphorescent layer and the absorption rate of the ultraviolet lights. Namely, in the art, with the premise of not to waste the source ultraviolet lights, it is almost impossible to achieve a satisfied illumination by forming the fluorescent or phosphorescent layer in a mono-layered scattering pattern. Yet, it is the primary object of the present invention to locate an efficiency solution that can make thinner the fluorescent or phosphorescent layer without sacrificing the cost in the ultraviolet energy. Also, thereby the energy can be reserved and the exhaustion of CO2 can be reduced to an acceptable degree.
Further, referring now to FIG. 16 and FIG. 17, a conventional design of an optical-film light tube is shown in a perspective view and a cross sectional view, respectively. As shown, the wall of the transparent tube 70 is coated by a fluorescent or phosphorescent layer as the visible light layer 71. Particles or powders of the visible light layer 71 are arranged in a form of multiple-layered piling and with a piling thickness (C) of about 30 μm to 60 μm (or 30 μm in average). Upon such an arrangement in the visible light layer 71, while the ultraviolet light 40 hits the particle to emit another light (the visible light), it is easy to see that only the surface particles on the fluorescent or phosphorescent layer 71 can be bombarded heavily by the ultraviolet lights. During the process, the particles distant to the surface of the visible layer 71 can contribute a pretty minor function in emitting the visible lights. Namely, the cost in building the distant portion of the visible layer 71 is wasted. Definitely, it is a topic worth to be resolved.
In addition, in the art of stimulating the short wave lights to produce the long wave lights at the visible light layer, conventional light-emitting elements such as the white LED, the discharge light tube (i.e., the hot cathode fluorescent lamp, HCFL), the cold cathode fluorescent lamp (CCFL), the induction lamp and the tiny discharge cell (applied to a plasma panel) are usually seen. The white LED is to project the ultraviolet lights onto the fluorescent or phosphorescent powders so as to emit white lights, or to project the blue lights onto the fluorescent or phosphorescent powders so as to emit corresponding yellow (red or green) lights for producing white lights after mixing the original penetrating blue lights. In general, the white light is consisted of 30% red light, 59% green light and 11% blue light.
Further, either the low-voltage mercury electric-discharge lamp or the electrodeless lamp is basically structured by a transparent glass tube having an interior fluorescent or phosphorescent coating with a predetermined thickness as the visible light layer. The average diameter of the tiny fluorescent or phosphorescent particles is about 2 μm to 20 μm, and the piling thickness is about 10 μm to 50 μm, or even up to about 100 μm. The transparent glass tube is filled thereinside by an electroluminescence (EL) mercury gas. Upon meeting an across voltage, the internal gas would be energized by an induced high voltage field or an induced magnetic field to emit ultraviolet lights. Then, the ultraviolet lights project on the fluorescent or phosphorescent layer so as to induce corresponding visible lights. The visible lights further penetrate the fluorescent or phosphorescent layer and leave the transparent glass tube to the outside. Upon such an arrangement, the aforesaid transparent glass tube having an interior fluorescent or phosphorescent coating can then perform as a light source. Nevertheless, some problems as described below do exist in the applications of the aforesaid low-voltage mercury electric-discharge lamp and the LED tube that uses the ultraviolet lights to generate the white lights.
On of the problems is the low yield of the ultraviolet lights. Because the fluorescent or phosphorescent layer is accumulated by plural tiny particles, and in order to obtain a sufficient amount of energy upon a single projection of the ultraviolet lights, the fluorescent or phosphorescent layer shall have a substantial thickness. However, a large thickness in the fluorescent or phosphorescent layer would affect the penetration rate of the induced visible lights definitely. In the current art, in order to obtain a better shining performance, the manufacturer usually reduces the thickness of the fluorescent or phosphorescent layer for the light tube. However, such a thin layer in the fluorescent or phosphorescent layer implies that a substantial amount of spacings with respect to the ultraviolet lights exists between the accumulated particles. Thus, some of the ultraviolet lights might not project on the particles but directly on the wall of the tube, such that the ultraviolet lights projecting on the wall would be absorbed by the wall and then be transformed into corresponding heat energy. Such a portion of the energy as the heat energy is then wasted in view of illumination purpose. It is interesting in the practice that a wide-acceptable criterion for coating the visible light layer is to have the ultraviolet lights with a predetermined strength to pair a visible light layer with a predetermined thickness. Namely, a stronger ultraviolet light is to pair a thicker visible light layer so as to obtain sufficient light absorption in the visible light layer upon a single projection of the ultraviolet light. However, under such a circumstance, the corresponding penetration rate of the visible lights in the fluorescent or phosphorescent layer would be reduced and thus the yield of the ultraviolet lights is definitely reduced as well. In a prior design of the optical-film lamp tube by the inventor himself as shown in FIG. 16 and FIG. 17, the yield of the ultraviolet lights is hiked up to 99.5%. It seems that the aforesaid ill-yield problem has been resolved by the prior design, but at least two following further problems are yet to be answered.
Problem I: Ill Penetration Rate Caused by Over Thickness in Visible Light Area
In the art, the fluorescent or phosphorescent particle is not instinctive transparent, and so the fluorescent or phosphorescent layer formed by piling the fluorescent or phosphorescent particles is consequently not transparent to the visible lights. An easy way to verify this argument is to fetch a T8 tube in the marketplace, place it without any voltage crossing between a naked eye and a visible light source, and demonstrate the truth that the visible lights of the visible light source are greatly blocked by the tube. Such a phenomenon is because that the visible lights must penetrate the poor-transparent tube (with the fluorescent or phosphorescent particles coated) before they can achieve the naked eye. In this experiment, for the fluorescent or phosphorescent layer in the tube is formed poor-transparently, so the naked eye can't see too much light from the visible light source. For a typical T8 tube in the marketplace, its monolayered fluorescent layer may reduce the penetration rate by about 40%. Such a reduction in the penetration rate is transformed into heat energy of the tube. In general, the average thickness of the piling particles (including at least 4-5 laminates of the particles) in the fluorescent area of the aforesaid tube is about 10 μm to 30 μm. Referring now to FIG. 18, an SEM view of a preferred tube in the market place is shown, in which the average diameter for the piling particles is about 3 μm, and the average piling thickness is about 15 μm. Please note that, even with such a thickness, the visible light layer still plays the major role to reduce the tube's brightness. Typically, the brightness of the tube would be reduced to 70% by this fluorescent layer.
Problem II: Blocking of Visible Lights by Crowd-Arranged Fluorescent or Phosphorescent Particles
It is comprehensive that a tight arrangement of the fluorescent or phosphorescent particles would affect the penetration of the visible lights. Even in the case that the visible light layer is consisted of a single layer of the fluorescent or phosphorescent particles, the crowding situation among particles would still reduce the penetration rate of the visible lights induced by having the ultraviolet lights to project on the fluorescent or phosphorescent particles. In general, only the induced visible lights that are limited to the ±15-degree area about the vertical normal line of the individual particle can be free to penetrate the visible light layer, and the rest of the induced visible lights would hit the neighboring particles at their travelling journals. In particular, the induced visible lights traveling inside the ±45-degree area about the horizontal normal light of the corresponding particle are definitely to be deflected by the neighboring particles, and thus the brightness contributed by the instant particle is substantially reduced. It got to be emphasized that, even with the involvement of the 0˜90-degree wide AOR ultraviolet optical film, spacing between crowd particles of the mono-layered fluorescent or phosphorescent layer is still large in an optical view. Thus, plenty of ultraviolet energy would be wasted as a form of heat to dissipate. Therefore, in a traditional design, at least four to five layers of particles are laminated so as to minimize the influence of inter-particle spacing and so as to obtain a better absorption of the ultraviolet radiations. Hence, it is easy to understand that in the art the fluorescent or phosphorescent layer with single-layered particles is commercially infeasible for the sake of energy conservations. This is the reason why no light tube using an ultraviolet source and applying only mono-layered particles can be seen in the marketplace.
The aforesaid discussion in the energy view for the traditional light tube prevails as well for the ultraviolet LED tube that introduces a blue light to project on the fluorescent or phosphorescent particles so as to induce the corresponding white light. Basically, in the art, the control variables are the inter-particle spacing of the fluorescent or phosphorescent layer and the capacity of the blue-light source. By providing over-rated blue lights to penetrate the fluorescent or phosphorescent particles that emit the yellow lights, the white light can be obtained by mixing the blue lights and the yellow or red-green lights induced by projecting the blue light on the fluorescent or phosphorescent layer. In the aforesaid discussion, the thickness or the inter-particle spacing of the fluorescent or phosphorescent layer must be predetermined, such that 11% of the blue lights can penetrate through the coating so as to become a part of the white light. Obviously, for a better white light mixing, the aforesaid thickness can't be made thinner, and also the inter-particle spacing can't be made larger to increase the transparency of the fluorescent or phosphorescent layer.
It is always a hope in the art that a preferred white light can be still formed by a mono-layered fluorescent or phosphorescent coating and also by a coating consisted of sparse scattering particles that are able to provide sufficient spacing. Then, the corresponding brightness for the light tube can be definitely and greatly improved.